The present invention relates to a system and method for controlling operation of ultraviolet lamps. More particularly, it relates to a system and method that efficiently operates an ultraviolet lamp otherwise serving to reduce or eliminate microorganisms propagating on an air conditioner cooling coil(s) of an air handling system.
Though invisible to the naked eye, a multitude of airborne germs (e.g., bacteria, mold spores, etc.) exist, many of which have adverse implications for humans. The likelihood of inhaling or contacting one or more of these microorganisms is elevated in enclosed areas, such as a home, office, etc. In most residential and commercial environments, an air handling system is in place, whereby outdoor air may be drawn into the home or building via a fresh air intake that merges with a return air duct, and then is subjected to heating or cooling conditions within the air handling system (e.g., via a furnace, air conditioner, etc.). The heated or cooled air is then forced through auxiliary ductwork back to the rooms or offices. Thus, airborne germs entrained in the incoming and return airflow are effectively xe2x80x9cconcentratedxe2x80x9d within the air handling system.
Efforts have been made to remove airborne contaminants from the intake (or return) air with filters, ultraviolet lamps, etc., that are fluidly connected to and/or positioned within the return air duct. Unfortunately, these techniques do not address an additional source of unwanted microorganisms. In particular, most air handling systems include one or more air conditioners. In general terms, the air conditioner includes a condenser unit and one or more cooling or evaporator coils. During use, the condenser cycles an appropriate refrigerant through the cooling coils that are positioned within a supply duct of the air handling system. Air is forced about or through the cooling coils. Heat is transferred from the air to the refrigerant, thereby cooling the air. As the refrigerant is heated, condensation along an exterior of the cooling coils occurs. This moist environment is an ideal breeding ground for microorganisms, especially mold spores. If left untreated, the microorganisms become entrained within the airflow and are subsequently directed to the room(s) or office(s) otherwise serviced by the air handling system, possibly leading to the health concerns highlighted above.
A highly viable solution to the above-described cooling coil related microorganism issue is to irradiate the cooling coil with ultraviolet energy or light. Studies have found that ultraviolet irradiation effectively eliminates most of the problematic microorganisms commonly generated on residential and commercial central air conditioner cooling coils. In general terms, an ultraviolet air treatment device useful for cooling coil applications includes one or more appropriately sized ultraviolet lamps that are positioned within the air handling system""s ductwork, in close proximity to the cooling coil. The ultraviolet lamp is normally mercury-based, with the ultraviolet air treatment device including a power supply ballast used to energize the mercury. One example of an acceptable ultraviolet air treatment device is available under the trade name xe2x80x9cEnviracaire Elite UV 100E Ultraviolet Air Treatment Systemxe2x80x9d from Honeywell Inc., of Golden Valley, Minn.
Efforts have been made to improve the life and operational characteristics associated with ultraviolet air treatment lamps. For example, non-ozone producing lamps are now available. However, the method of controlling operation of the ultraviolet air treatment device for cooling coil irradiation applications has essentially remained unchanged. In particular, the ultraviolet lamp(s) is simply powered on following installation, and is never shut off. Regardless of whether the air conditioner is active or inactive, the ultraviolet lamp(s) stays on twenty-four hours a day. While viable, this approach is quite inefficient in that when the air conditioner is inactive for extended periods of time, there is (and has been) no condensation forming on the cooling coil, and thus no xe2x80x9cnewxe2x80x9d microorganisms (e.g., mold spores) being generated, so that powering of the ultraviolet lamp is of limited value. As a result, continuous powering of the ultraviolet lamp needlessly consumes a relatively substantial portion of the lamp""s useful life, thereby requiring more frequent lamp replacement (and thus increased maintenance costs) and excess energy consumption. Alternatively, the user may be instructed to manually turn the ultraviolet lamp off when it is expected that the air conditioner will not be used (e.g., winter season), and then turn the ultraviolet lamp on when air conditioner use is expected (e.g., summer season). Obviously, a user may forget to perform these activities, resulting in inefficient ultraviolet lamp operation when the air conditioner is not in use and/or failure to use the ultraviolet lamp when removal of cooling coil-generated microorganisms is necessary. Similarly, the user may incorrectly decide that the air conditioner will not be in use, or vice-versa.
Ultraviolet air treatment devices continue to be highly popular for removal of airborne germs. In fact, ultraviolet air treatment devices are now being advocated for treating or irradiating air conditioner cooling coils. Unfortunately, the currently employed technique for operating an ultraviolet air treatment device in a cooling coil environment overtly decreases a useful life of the ultraviolet lamp and, where a user is required to estimate appropriate usage, may not be turned on when needed. Therefore, a need exists for a system and method for efficiently controlling an ultraviolet air treatment device used to irradiate microorganisms occurring on an air conditioner cooling coil of an air handling system.
One aspect of the present invention relates to a method of controlling operation of an ultraviolet air treatment device including an ultraviolet lamp positioned to irradiate an air conditioner cooling coil associated with an air handling system. The method includes electrically connecting a controller to the ultraviolet air treatment device such that the controller can dictate activation and deactivation of the ultraviolet lamp. A first control sequence is then performed whereby the controller automatically cycles the ultraviolet lamp between a powered on condition for a first predetermined time period and a powered off condition for a second predetermined time period. In this regard, the ultraviolet lamp irradiates the cooling coil in the powered on condition. In one preferred embodiment, the first and second predetermined time periods are both three hours. In another preferred embodiment, the method further includes monitoring an operational mode of the air conditioner (with the air conditioner operating in either a cooling mode or a non-cooling mode). Further, a transition routine is initiated upon determining that the operational mode has switched from cooling to non-cooling. In this regard, the transition routine includes controlling operation of the ultraviolet lamp in accordance with the first control sequence as identified above for a predetermined length of time. In an even more preferred embodiment, the transition routine extends for thirty days, with the method further including operating the ultraviolet lamp in accordance with a second control sequence if the air conditioner remains in the non-cooling mode throughout an entirety of the thirty-day transition period.
Another aspect of the present invention relates to a control system for controlling operation of an ultraviolet air treatment device. In this regard, the ultraviolet air treatment device includes an ultraviolet lamp positioned to irradiate an air conditioner cooling coil associated with an air handling system. With this in mind, the control system includes an activation device and a controller. The activation device is electrically connected to the ultraviolet lamp for selectively powering the ultraviolet lamp on and off. The controller is electrically connected to the activation device and is adapted to store a first and second predetermined time period. Further, the controller is adapted to perform a first control sequence in which the controller automatically cycles the ultraviolet lamp between a powered on condition for the first predetermined time period and a powered off condition for the second predetermined time period. In one preferred embodiment, the control system further includes a temperature sensor electrically connected to the controller and positioned within the air handling system for providing temperature information indicative of an operational mode of the air conditioner. With this one preferred embodiment, the controller is adapted to determine the operational mode of the air conditioner based upon the temperature information.